Vamiga: Background glitches on Bubba 'N' Stix (Core Design).

[Gianmarco72]

There's a problem with the mountains in the background: they disappear with every Bubba's step.

Here they are:

... now they are gone:

Maybe a "sprite tricks"?

Also tested on UAE and it's ok 👍🏻

[dirkwhoffmann]

Maybe a "sprite tricks"?

Excellent opportunity to try out the new stencils feature from the Monitor panel 😎.

Using the stencil tool, it is possible to cut out certain graphics layers such as the sprite layers. Applying the feature to this game results in the following image:

It is clearly not related to sprites this time.

Let's revert to the usual procedure: X-raying the patient 🤒.

Wooaaaaahhhh, another game that maxes out the Blitter to the last free DMA cycle 😬.

There is heavy Copper activity in the mountain area, so I bet it's another issue with register access timing.

Next step: Put on safety goggles and have a look at the Copper list ☢️. We need to find out the registers that get modified by the Copper in this are.

[Gianmarco72]

Excellent opportunity to try out the new stencils feature from the Monitor panel 😎.

Very cool!! 😃
I don't see the stencils feature ...

... will it be in a future release?

[dirkwhoffmann]

I don't see the stencils feature ...

Latest hot stuff from vAmiga engineering 😎. Top secret. Not yet released.

It's a nice feature to quickly see where the visible pixels come from. E.g., here is the original Cabal intro which uses a two-layer scrolling effect:

These pixels stem from playfield 1:

And those from playfield 2:

[dirkwhoffmann]

It is clearly not related to sprites this time.

Well, it turned out that this is not really true. Actually, it is all about sprites. The code changes that fixed "Brian the Lion" fixed this issue, too.

The following image shows all sprite layers together:

And here is sprite 7 only:

Bottom line: The mountain parallax effect is all done with sprites.

There is another parallax layer at the bottom which has been done the traditional way (in dual-playfield mode). These pixels belong to the second playfield: